Cutting drifts having teeth on their sides, similar to large file-teeth, are shaped by two methods; small ones not more than an inch thick being grooved by filing, and large ones that may be three or four inches thick being grooved with a planing-machine or shaping-machine.

The steel suitable for drifts is a tough, well-hammered metal that has not been cast, and the smaller the intended tool the greater is the need to select an elastic fibrous metal which will bend after being hardened, and not be liable to crack in hardening through being too solid. Small thin drifts may be made of a hard Swedish iron, and afterwards partly carbonised to steel the exterior. A drift thus made will sustain a severe bending while in a crooked hole, without being so liable to break as if the entire tool were of steel. The short drifts do not bend while being hammered through a piece of work; they may therefore be made of steel; but all long ones that are comparatively thin are more pliable if made of iron. The hammering of any drift, whether long or short, shakes and tends to break it, and it is advisable to make each one as short as its intended work will permit. Those for drifting small holes often require long handles, similar to that shown in Fig. 576 ; such a handle is thinner than the portion for cutting, that all its teeth may be driven through the work. Fig. 577 denotes a taper drift having a thick handle, which is an effectual means of strengthening the tool, a portion of the part having teeth being always outside the work to be drifted. Such a handle is also necessary for dislodging the tool after being tightly hammered into a hole, when the small end of the cutting part cannot be hammered to loosen it; in such cases, hammering the handle sideways must be performed.

The forging of such tools depends on their sizes. A small short drift is made without forging, by shaping the intended tool at one end of a short bar, and cutting of the tool with an edge of a file, after all the teeth are finished. The forging of a parallel drift with a handle is effected by reducing the handle or stem from a piece of steel or iron which is thick enough to become the cutting portion without upsetting. Another course is adopted to make a taper drift with a handle, and consists in tapering both ends of a piece to produce a thick portion in the middle; this thick portion becomes the large end of the cutting part, and also the junction of the handle, the thin portion at one end of the work being made into the drift's handle, and the other thin end being formed into the taper end for cutting.

While forming the teeth, the grooves are made only deep enough to allow sufficient room for the small shavings that are cut off while hammering, that the tool may not be weakened with deep grooves. In order to produce strong teeth, about a quarter of an inch should be allowed between any two contiguous cutting edges, if the drift is not more than an inch wide; large ones require teeth about half an inch apart; if the teeth are too close, the angle of the slant surface which extends to each 'cutting edge, will be too acute, and cause the teeth to break with the severe hammering which a large drift requires.

Filing is the means adopted for shaping the teeth of small drifts, the four blank sides being first carefully flattened and smoothed, that the places for the teeth may be properly marked. The marking is effected with a divider and scriber, the divider being used to place the teeth at equal distances apart, and the scriber used with a straight-edge to mark the lines upon the broad sides of the tool. These lines are inclined about fifteen degrees to the length of the tool, and are marked on all the four broad sides, if a safe-side is not required. When the marking is completed, a rough three-cornered file is employed to commence the grooves, by filing near to each straight line, which indicates the place for each intended cutting edge. This filing roughly shapes the cutting edges, and also the slant surfaces extending to each edge, these slant portions being afterwards finished with a smooth three-cornered file, or with a smooth half-round file. The finishing of the cutting surfaces, also, should be done with a smooth three-cornered file, because it is necessary for each cutting edge to stand at right angles to the length of the tool, and such a form cannot be easily obtained with a right-angular file, usually termed a flat file. After a proper smooth filing, the cutting edges are polished with flour-emery cloth wrapped around the same smooth file used for filing.

The teeth of large drifts are formed by planing. After the places for the intended teeth are scribed, the tool is put upon the planing-table of a shaper with the length of the drift properly inclined to the direction of the tool's motion, in order to incline the intended teeth to the proper position. If the drift is a short one, without a handle, it is held on a plate and properly wedged up, if the drift is taper, and fastened at each end with a screw-bolt and plate, and fixed at the middle with poppets. A short one may be thus held with a plate on each end, because it is seldom necessary to make teeth along the entire length of a drift, however short it may be. A parallel drift with a handle is partly held on the machine by gripping the handle, and teeth may then be made at the junction of the handle with the part for cutting, if the thickest portion of the tool is at the junction.

The shapes for the teeth of drifts are represented in Fig. 575, and if produced by planing, the tools required are grooving tools having short grooving parts, to prevent bending while at work. Of such a grooving tool the extremity of the cutting edge is flat, and also bevelled to the proper bevel, to produce the desired slant surface which is to extend to each cutting tooth. Such a tool will smoothly shape the teeth, if soapy water is applied, so that but little smooth filing with a three-cornered file is afterwards required.